Electric lamp and mounting



March 24, 1942. CE'ADER 2,277,633

. ELECTRIC LAMP nn MOUNTING Filed Jan. 8; 1938 Inventor: Joseph D.'Ceader;

Patented Mar. 24, 1942 7 ELECTRIC LAMP AND MOUNTING Joseph D. Ceader, East Cleveland, Ohio, assignor to General Electric Company, a. corporation of.

New York Application January s, 1938, Serial No.184,046

2 Claims.

My invention relates to electric incandescent lamps or similar devices comprising an electric energy translation element, such as a filament,

' sealed within a bulb or envelope. More particu- In the use of miniature lamps for flashlight and similar service, wherein the lamp is mounted in a reflector memben'it is desirable that the filament be accurately located at the focal point of such reflector member in order to obtain the most emcient beam of light. Accordingly, one object of my invention is the provision of means for simply and accurately centering the filament of a flashlight or similar lamp with respect to the focal point of a reflector. Another object of my invention is the provision of an electric incandescent lamp of the prefocused type, in which the filament is mounted in predetermined relation with respect to a reflector-engaging shoulder on the bulb. Still another object is to provide a lamp having a cylindrical bulb with the filament located between the said shoulder and the tip or forward end of the bulb so that the lamp may be inserted in a reflector from the rear.

Further objects and advantages of my invention will appear from the following description of a species thereof and from the accompanying drawing.

In the drawing, Fig. 1 is a longitudinal 'sectional view through the bulb of a lamp comprising my invention, showing the manner in which the filament is mounted in predetermined relation with respect to a portion of the bulb during the sealing-in operation; Fig. 2 is a longitudinal sectional view of a completed lamp comprising my invention; and Fig. 3 is a longitudinal view, partly in section, showing the manner in which a lamp comprising my invention may bemounted in the reflector member of a flashlight to accurately position the lamp filament at the focal point of such reflector member.

' Referring to the drawing, the particular lamp illustrated is of the conventional butt-sealed miniature type used, for example, in flashlights. The lamp comprises a bulb ID of cylindrical shape and is provided with an annular protuberance adjacent its lower or base end |2, to which end is sealed an exhaust tube I3. A pair of leading-in wires I4, l5 have portions thereof sealed in the 'joint formed by the bulb l0 and exhaust tube l3. A filament I6 is mounted on the leading-in wires l4, I5 which are held in spaced relation within the bulb by a bead ll of insulating material. The filament I6 is accurately mounted within the bulb-at a'predetermined distance d from, and; in apredetermined plane (preferably with respect to a plane A-A passing through the forward shoulder portion l8 of the annulus H of the bulb at right angles to' the longitudinal axis of said bulb. This plane A--A represents theline of engagement'between the bulb seal holder |9 (Fig. 1) and the annulus during the sealing-in operation. The location of the plane A- -A along the longitudinal axis of the bulb-is therefore determinedby. the diameter of the ring-engaging edge 20 of the opening 2| in the bulb seal holder.

The base 22 comprises a cylindrical metal shell 23 provided at its outer end with a body of insulating material 24, preferably glass, having an opening 25 therein, and a metal eyelet 26 fused to the end thereof.- The'leading-in wire I5 is threaded through the base insulating opening 25 and electrically connected to the metal eyelet 26, such as by soldering, to thereby form the end contact 21. The other leading-in wire I4 is bent back over the inner edge or rim of the base shell 23 and soldered to the outer surface of said shell, as shown at 28 in Fig. 2. The base 22 is secured to the bulb by a quantity of cement 29.

Fig. 3 illustrates a method of mounting a lamp comprising my invention ina flashlight reflector so as to accurately position the filament at the focal point of the same. The reflector 30 is formed with a centrally located opening 3| the diameter of which is exactly the same as that of the opening 2| in the bulb seal holder at the bulbengaging edge 20 thereof. The lamp is inserted in the reflector opening 3| from the rear of the reflector, and the annulus M on the bulb is shoulder portion l8 of the annulus ll along the previously referred to plane A-A. The filament I6 01 the lamp will therefore be positioned at the distance d from the rear edge of the reflector opening 3|. By making this distance d'exactly equal to the distance of the reflector focal point from the rear edge of the reflector opening 3|,

the lamp filament It will be accurately located at such focal point.

The flashlight casing or housing 36 may be provided with additional lamp support means comprising a plurality of light spring fingers 31 mounted on a fibre washer 38 and adapted to engage the lamp base shell 23 and maintain the lamp in alignment with the longitudinal axis of the casing 38. At the same time, these spring fingers 31, m conJunction with the switch contact arm 39 and switch It, constitute the electrical connection between the base shell 23 and the casing 36. 1

If desired, the spring member 32 between the lamp end contact 21 and the battery center contact 34, together with its supporting fibre disc.33,

. may be omitted and only the conventional spring 4| at the rear of the battery casing, between the end cover 42 thereof and the battery 35, used to force the annulus ll into engagement with the rear edge of the reflector opening 3|.

' While the annulus H on the bulb is the preferred form of construction, the bulb, ifdesired,

may be provided instead with three or more outwardly extending protuberances or projections spaced approximately equally around the circumference of the bulb. Such projections will into said reflector from the rear thereof, said bulb having an integral outwardly extending annulus thereon forming a shoulder facing forwardly ,of the bulb and engaging the rear of said reflector around the said opening therein and a concentrated light source located in the portion of said bulb' within said reflector at a definite predetermined distance from the plane of the forward face of said shoulder, and means behind said reflector for engaging said lamp and pressing the said forward face of said shoulder thereon in engagement with the rear of said reflector to hold the said light source in definite relation to the focus of said reflector.

2. In a flashlight, the combination of a casing, a concave reflector within said casing having a centrally located opening therein, an electric lamp comprising a tubular bulb extending into said reflector from the rear thereof, said bulb having an integral outwardly extending annulus thereon forming a shoulder facing forwardly of the bulb and engaging the rear of said reflector around the said opening therein and a concentrated light source located in the portion of said bulb within said reflector at a definite predetermined distance from the plane of the forward face of said shoulder, and means within said casing behind said reflector for engaging said lamp and pressing the said forward face of said shoulder thereon in engagement with the rear of said reflector to hold the said light source in deflnite relation to the focus of said reflector.

JOSEPH D. CEADER. 

